JPH11320652A - Composite tube molding die - Google Patents

Abstract

(57) [Summary] [Problem] Mold closing accuracy does not change. A composite tube molding die 1 includes a die ring 2, an outer layer mandrel 3, and an inner layer mandrel 4, wherein a die center axis L is provided.
The inner mandrel 4 is provided so as to close the mold along the inner layer.
Molten resin 50 extruded from the resin flow path 5 between the outer layer mandrel 3 and the molten foamed resin 6 extruded from the foamed resin flow path 6 between the outer layer mandrel 3 and the die ring 2.
0 to form a composite tube 7.
At the base end of the outer layer mandrel 3 in the molding direction, a mold center axis L
A flange 30 having a tapered surface 32 inclined with respect to is provided, and the tapered surface 22 that can be butt-joined to the tapered surface 32 is formed on the die ring 2,
The mold is closed by butt joining the tapered surfaces 32 and 22 together.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for forming a resin composite tube in which a resin layer and a foamed resin layer are combined.

[0002]

2. Description of the Related Art Generally, an outer layer mandrel and an inner layer mandrel are provided inside a die ring, and a molten resin extruded from a resin flow path between the inner layer mandrel and the outer layer mandrel and a gap between the outer layer mandrel and the die ring. 2. Description of the Related Art A composite pipe molding die for forming a composite pipe by compounding a molten foamed resin extruded from a foamed resin flow path is known (for example, Japanese Patent Application Laid-Open No. 5-169574, Japanese Patent Publication No. 1-284848). Reference).

Conventionally, as shown in FIG. 4, this composite pipe molding die a has a substantially cylindrical outer layer mandrel c.
Is inserted into the die ring b and the outer peripheral cylindrical portion e of the outer layer mandrel c is located closer to the molding base end than the foamed resin flow path d.
And the inner peripheral surface f of the die ring b, and the mold is closed.

[0004]

However, in the case of the above-described conventional composite pipe molding die a, the outer cylindrical portion e of the outer layer mandrel c and the inner peripheral surface f of the die ring b are closed so that the die is closed. Therefore, if the dimensions of the outer peripheral cylindrical portion e of the outer layer mandrel c and the inner peripheral surface f of the die ring b change due to the re-plating repair of the mold or the like,
The mold closing accuracy of both also changes. Therefore, a gap is formed in the portion where the outer layer mandrel c and the dyne rig b are fitted, and the foamed resin flow path d
However, there is a disadvantage that the molten foamed resin flowing through the melt enters and stagnates, and is thermally decomposed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a composite tube molding die in which the closing accuracy does not change.

[0006]

According to the present invention, there is provided a composite tube molding die provided with a die ring, an outer layer mandrel and an inner layer mandrel which are closed along the center axis of the die. The molten resin extruded from the resin flow path between the inner layer mandrel and the outer layer mandrel, and the molten foamed resin extruded from the foamed resin flow path between the outer layer mandrel and the die ring to form a composite pipe. In the composite pipe forming mold made in the above, a flange having a tapered surface is provided at a base end portion of the outer layer mandrel in the forming direction, and a tapered surface that can be butt-joined to the tapered surface is formed on the die ring. The mold is closed by butt joining of the tapered surfaces.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows the overall structure of a composite pipe molding die 1, and FIG. 2 shows a composite pipe molding line using the same.

That is, the composite tube forming die 1 comprises a die ring 2, an outer mandrel 3 and an inner mandrel 4.
Is provided so as to close the mold along the mold center axis L,
The molten resin 50 flowing from the inlet 81 of the connection base 8 into the resin flow path 5 and the molten foam resin 60 flowing from the inlet 20 of the die ring 2 into the foamed resin flow path 6 are combined with the die head 2.
3 to form a composite tube 7;
The tapered surface 32 of the flange 30 provided on the outer layer mandrel 3 and the tapered surface 22 provided on the die ring 2 are joined to close the mold.

The die ring 2 is formed in a thick cylindrical shape. On the inner peripheral surface of the die ring 2 at the base end in the molding direction, a groove 21 oblique to the center axis L of the mold is provided over the entire circumference. An inlet 20 of the molten foaming resin 60 communicating with the outer peripheral surface of the die ring 2 is provided at a portion of the groove 21 located at the base end in the molding direction at right angles to the center axis L of the mold. Have been. As described above, since the groove 21 is inclined with respect to the mold center axis L, the molten foamed resin 60 from the inflow port 20 allows the groove 2
1 stagnation in the part located at the tip of the molding direction,
Without being insufficiently distributed, the ink uniformly spreads over the entire groove 21 and smoothly flows from the groove 21 to the foamed resin flow path 6. The base end of the dyne rig 2 in the forming direction is cut obliquely in accordance with the groove 21 to form a tapered surface 22. Further, a die head 23 is provided at the tip of the die ring 2 in the forming direction.

The outer mandrel 3 has a substantially cylindrical main body portion 31 which can be inserted into the inner peripheral surface of the die ring 2. Also, the outer layer mandrel 3 is
A cylindrical flange portion 30 having substantially the same thickness as the die ring 2 is formed at the base end of the molding direction 1. This collar 3
At 0, a tapered surface 32 that matches the tapered surface 22 of the Dyne rig 2 is formed. The tapered surface 22 of the die ring 2 and the tapered surface 32 of the outer layer mandrel 3 are butt-joined, whereby the die ring 2 and the outer layer mandrel 3 are mold-closed, and the foamed resin flow path 6 is formed therebetween. You. The flange 30 of the outer layer mandrel 3 is configured to connect the connection base 8 of the extruder 11 to a surface opposite to the tapered surface 32.

The inner layer mandrel 4 is formed in a rod shape to be inserted into the inner peripheral surface of the outer layer mandrel 3. The inner layer mandrel 4 forms a resin flow path 5 between the die head 23, the outer layer mandrel 3, and the inner peripheral surface of the connection base 8.

As shown in FIG. 2, the molten resin 50 is supplied from the extruder 11 to the resin flow path 5 of the composite tube molding die 1 through the connection mouth 8 in the composite tube molding die 1 thus constructed. Also,
The molten foamed resin 60 is supplied from the sub-extruder 12 to the foamed resin channel 6 via the inlet 20 of the die ring 2. After the molten resin 50 and the molten foamed resin 60 are combined by the die head 23, they are extruded into a cylindrical shape, and are expanded by the diameter expanding mold 13 provided at the tip of the die head 23.
While being taken up by the take-up machine 14 at a speed higher than the extrusion speed, it is formed in the cooling water tank 15 to form the composite pipe 7. Further, the composite pipe 7 is cut into an appropriate length by the cutting machine 16 at a position after being taken up by the take-up machine 14.

According to the composite tube forming die 1, the tapered surface 22 of the die ring 2 and the tapered surface 32 of the flange portion 30 of the outer layer mandrel 3 do not form a joint, so that re-plating repair of the die and the like are performed. However, the tapered surface 22 of the die ring 2 and the tapered surface 32 of the outer layer mandrel 3 can be exactly butted and joined to each other, thereby preventing a change in mold closing accuracy. Therefore, it is possible to prevent the foamed molten resin 60 from being stagnated and decomposed in the gap generated due to the deterioration of the mold closing accuracy, and forming a composite pipe containing the decomposed resin.

In this embodiment, the die 2
Has a fixed length, but as shown in FIG. 3, an appropriate number of (two in this embodiment) die rings 2 are combined in accordance with the length of the outer layer mandrel 3, and the approach and land length are adjusted. May be adjustable. Further, as shown in the figure, the die ring 2 may be provided between the flange portion 30 of the outer layer mandrel 3 and the connection base 8 according to the length of the inner layer mandrel 4. .

[0016]

As described above, according to the present invention, a flange having a tapered surface inclined with respect to the center axis of a mold is provided at the base end of the outer layer mandrel in the molding direction.
The die ring is formed with a tapered surface that can be joined to the tapered surface, and the die is closed by joining the tapered surfaces. Therefore, the outer layer mandrel and the die ring do not come into contact with each other when the die is closed. Therefore, it is possible to prevent the mold closing accuracy between the outer layer mandrel and the die from being changed by performing re-plating repair of the mold or the like. In addition, it is possible to prevent degradation of the foamed resin in the mold due to deterioration of the mold closing accuracy and the occurrence of decomposition.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing an overall configuration of a composite pipe molding die according to the present invention.

FIG. 2 is a schematic view showing a composite pipe production line using the composite pipe molding die shown in FIG.

FIG. 3 is a cross-sectional view showing another embodiment of the composite tube molding die according to the present invention.

FIG. 4 is a cross-sectional view showing a conventional composite tube molding die.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 composite tube molding die 2 die ring 22 tapered surface 3 outer layer mandrel 30 flange 32 tapered surface 4 inner layer mandrel 5 resin flow path 50 molten resin 6 foamed resin flow path 60 molten foamed resin 7 composite pipe L mold center axis

Claims (1)

[Claims] A die, an outer layer mandrel, and an inner layer mandrel are provided so as to close a mold along a center axis of a mold, and a molten resin extruded from a resin flow path between the inner layer mandrel and the outer layer mandrel; A composite pipe molding die formed by molding a composite pipe by compounding a molten foamed resin extruded from a foamed resin flow path between a mandrel and a die ring, wherein a molding direction base end of an outer layer mandrel is formed. A flange having a tapered surface that is inclined with respect to the center axis of the mold is provided, and a die ring is formed with a tapered surface that can be butt-joined to the tapered surface. A composite tube molding die, wherein the die is closed.